In a CA (carrier aggregation) technology, multiple contiguous or non-contiguous carriers are aggregated to form larger bandwidth (a maximum of 100 MHz), so as to meet a requirement for a higher rate and improve utilization of a discrete spectrum.
A HetNet (heterogeneous network) is used as an important evolution solution, and the solution implements precise coverage of a mobile communications network, significantly improves network performance, and brings better experience of a voice and a mobile data service to a user. A network side of the HetNet may include a core network, a transport network, and a base station. User equipment communicating with the network includes UE (user equipment) that has a CA capability and UE that does not have a CA capability.
The UE that has a CA capability is used as an example. When the HetNet performs data transmission in a CA manner, an EPC (evolved packet core) network delivers data information to the UE by using both a primary base station and a secondary base station, and the UE needs to send a feedback to the primary base station, where the feedback is used to indicate a receive status of the data information delivered by the primary base station and/or the secondary base station. In the prior art, the secondary base station allocates a PDSCH (physical downlink shared channel) resource and a PDCCH (packet data control channel) resource to the UE, and requests, from the primary base station, a data block to be sent to the UE. After receiving the data block delivered by the primary base station, the secondary base station determines an identifier of a PUCCH (physical uplink control channel) code channel resource. The secondary base station sends the identifier of the PUCCH code channel resource to the primary base station, and sends the data block and the identifier of the PUCCH code channel resource to the UE. The UE sends, on the corresponding PUCCH code channel resource, a feedback on the data block according to the identifier of the PUCCH code channel resource. After receiving, on a corresponding PUCCH code channel, the feedback according to the identifier of the PUCCH code channel resource, the primary base station may demodulate the feedback. A feedback obtained by means of demodulation may include two types: a NACK (negative acknowledgement) and an ACK (acknowledgement). The secondary base station needs to perform HARQ (hybrid automatic repeat request) retransmission on data corresponding to the NACK. The foregoing data transmission process has relatively low transmission efficiency.